[MITgcm-support] documentation about OBC Orlanski and Balance Flow

[Camille Mazoyer]

Le 01/02/2016 17:17, Martin Losch a écrit :
> Hi Camille,
>
> I think the balance-flow option is properly described in the docs. It’s just a correction after the conditions have been computed.
> The Stevens BC are now available for all boundaries (although I have to admit, that I used and tested the E-W boundaries the most)
Great new! So I can try it also in a simulation.
> You can also mix the BCs, ie. have Stevens for one boundary and Orlanski for another, and neither for a third boundary.
Ok. I will think about these ideas!
>
> For details of the Orlanski BCs you’ll probably have to read the code (and refer to textbooks), I am afraid.
Yes, indeed. I began to do that. I translate the OBC_Balance routine 
into numerics, and I read the Orlanski routine also. But it's not always 
easy to understand it for a MITgcm beginner :-)

Thanks for all, and for taking time to answer me,
Camille
>
> Martin
>
>> On 01 Feb 2016, at 16:22, Camille Mazoyer <mazoyer at univ-tln.fr> wrote:
>>
>> Hi,
>> Thank you for your reply Matthew and Martin. I already read the doc http://mitgcm.org/public/r2_manual/latest/online_documents/node236.html, but I didn't try the examples. I will run these examples very soon. I already did google "mitgcm + OBC", and as you said, and I found a lot of discussion, but I didn't see yet an explanation of OBC_balance or how Orlanski  method is implemented. But, I will search again if some discussions can help me.
>> The Stevens BCs  are currently only implemented for eastern and western boundaries no? So if I have 3 boundaries (Eastern, Wester, South), I can't use it no? Or can I mixed Orlanski for South boudary and Stevens for Eastern and Western?
>>
>> Thank you,
>> Camille
>>
>>
>> Le 29/01/2016 09:31, Martin Losch a écrit :
>>> Hi Camille,
>>>
>>> there is some documentation about the obcs package here: <http://mitgcm.org/public/r2_manual/latest/online_documents/node236.html>
>>> There is very little about the Orlanski option but at least it points you to some examples (the verification experiments that Matt mentioned).
>>>
>>> I often use the Stevens BCs, which are some kind of mixture of prescribe values and a radiation condition. For purely radiative BCs, the Orlanski option is probably the best.
>>>
>>> Martin
>>>
>>>> On 28 Jan 2016, at 16:52, Camille Mazoyer <mazoyer at univ-tln.fr> wrote:
>>>>
>>>> Dear all,
>>>> I just start using MITgcm as I will use it during my thesis for creating a configuration on the rade de Toulon, France.
>>>> Currently, I'm trying to understand how open boundary conditions work, with these two steps:
>>>> - orlanski scheme wich seems to be a predictor step, if I understand well, where we use the pression of the previous step. We calculate velocities, temperature and salinity we will have to correct during the next step
>>>> - use of balance flow wich seems to be a corrector step of these variables (Is this right?)
>>>> I only find a few explanations in the doc (mainly explaining the CPP Key). I also have read the paper of Orlanski, 1976.
>>>> Would you have more documentations / publications about the method used in the MITgcm (orlanski and balance flow)? (about the numerical part, or the method, ...)
>>>>
>>>> Thank you very much for your help,
>>>> Camille Mazoyer
>>>>
>>>> -------------------------------
>>>>
>>>> Camille Mazoyer
>>>> Phd Student
>>>> Mediterranean Institute of Oceanography (MIO)
>>>> Université de TOULON
>>>> Bat X - CS 60584
>>>> 83041 TOULON cedex 9
>>>> France
>>>> http://mio.pytheas.univ-amu.fr/
>>>>
>>>>
>>>>
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>> -- 
>> ------------------------------------------
>> Camille Mazoyer
>> Phd Student
>> Mediterranean Institute of Oceanography (MIO)
>> Université de TOULON
>> Bat X - CS 60584
>> 83041 TOULON cedex 9
>> France
>> http://mio.pytheas.univ-amu.fr/
>>
>>
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>
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-- 
------------------------------------------
Camille Mazoyer
Phd Student
Mediterranean Institute of Oceanography (MIO)
Université de TOULON
Bat X - CS 60584
83041 TOULON cedex 9
France
http://mio.pytheas.univ-amu.fr/